Preheater for oil for refinery crackers



w. w. KEMP 2,430,344

PREHEATER FOR OIL FOR REFINERY CRACKERS Nov. 4, 1947.

Filed Sept. 8, 1944 2 Sheets-Sheet l I v Q Q Q I Nov. 4, 1947.

w.'w. KEMP PREHEATEH FOR OIL FOR REFINERY CRACKERS Filed Sept. 8, 1944 2Sheets-Sheet 2 Patented Nov. 4, 1947 PREHEATER FOR OIL FOR REFINERYCRACKERS William Wallace Kemp, Baltimore, Md., assignor to The C. M.Kemp Manufacturing Company, Baltimore, Md., a corporation of MarylandApplication September 8, 1944, Serial No. 553,173

8 Claims.

Oil heaters for petroleum crackers have the common disadvantage of beingso constructed and operated that the heat application is at timeslocalized and the temperature excessive, there beingactual flame contactwith the oil pipes resulting in over-heating of the pipes, carbonizingof the oil and actual blistering of the pipes. These blisters finallybreak away permitting the oil to leak into the furnace or combustionchamber where it burns, due to the excess of air pulled through thefurnace by the stack. The oil pipes burning out cause frequent failureand shutdown of the oil heater and consequently of the cracker.

The oil should be pro-heated to a temperature of about 850 degreesFahrenheit. The flame of combustion of natural gas, still gas or fueloil, when mixed with the proper amount of air, will have temperatureswhich will approach if not exceed 3000 degrees Fahrenheit; hence, thedanger of flame contact with the oil pipes is apparent. Thirty percentexcess air is usually provided; this forms zones of high oxygen contentand promotes deterioration and pipe oxidation.

Purposes of this invention, among others not specifically mentioned, areto use as a fuel a complete air-gas mixture such as can be produced bythe proportioning air and gas mixing machines described in U. S. LettersPatent to W. W. Kemp et al.: 1,771,223, July 22, 1930, and. 1,880,141,September 27, 1932, which complete air-gas mixture produces a short,stiff blast flame which when directed within a tube or cylinder at acentral point, produces a discharge or blast of combustion gases at thedischarge end of the tube while entraining combustion gases at thebottom or inlet end. In this invention there are a number of these tubesplaced preferably in vertical position and in rows, each entrainingcombustion gases from the floor of the heater and discharging toward theceiling, thus setting up a circulation of the atmosphere within theheater chamber.

The greater the pressure at which the air-gas mixture is fed to theseveral burners, the stiffer the blast flame, the more rapid thecirculation, consequently, the more uniform the heat distribution. Theexhaust openings and pipes are at the bottom of the chamber so that thechamber will fill with gas, and thus maintain a uniform temperature inthe whole chamber. Because the air-gas ratio is about complete orcorrect for complete combustion, no air is drawn in by inspiration oraspiration, and the flame is short,

entirely confined within the tubes and cannot contact any of the oilpipes, and subject to close control, the differential between thetemperature of the gases and oil is kept low, to prevent over heatingand damage to the heater. The oil pipes are heated by the rapid passageand circulation of the combustion gases among them. A thermostat placedwithin the heater and in the passage of the circulating gases isadjusted to limit the temperature of these gases. A second thermostatplaced in an oil duct outlet will vary the volume of fuel burned tocontrol the temperature of the oil.

With the furnace of this invention, there is no stack, chimney orexhaust fan. The pressure at which the combustion gas and air mixture isfed to the burners controls the circulation of the combustion gases, andthe pressures at which these gases exhaust from the heater. There isvery slight pressure drop of gases through the heater, the combustiongases exhaust through openings in the floor of the heater and arecarried through a duct to a convection heater for preliminary heating ofthe oil and finally through heat exchangers or coolers and dryers.

Another purpose of this invention is to supply inert gas, the deviceserving the double purpose of an oil heater and an inert gas generator.The inert gas is required in the oil refinery for purging. producinginert blanketing atmosphere and, when compressed and dried, can be usedfor instrument operation.

The complete air-gas mixture above referred to produces the highest andmost uniform flame temperature. It is common practice to so adjust theKemp air and gas proportioning machine, patent numbers previouslyreferred to, to obtain a combustion gas having one-half per cent or lessof oxygen and no monoxide, or one-half per cent or less of monoxide andno oxygen, either of which is an ideal inert gas for refinery purposes,especially when the water vapor content is reduced to the desired extentby the heat exchanger or desiccant towers. Under present operatingconditions, a broken or leaky oil pipe within the heater can result in abad fire, flame occurring within the heater and. extending to the top ofthe stack, the atmosphere in the entire system being such as to supportcombustion. With the apparatus of the present invention, the atmosphereis inert and should an oil leak occur, the petroleum actually playing onthe gas flames, the oil and the'oil vapor actually could not ignite orcombust, as there is no oxygen present to support combustion.

The heater is under a pressure of inert gas of from a few ounces to onepound or more; therefore, it is not possible for atmospheric air to leakin. Should the air and gas mixture flame contact a combustion blasttube, oil piping or any other surface after the mixture is ignited atthe face oi the; burner, the combustion would. be retarded, theflamecooled somewhat. and monoxide gas produced. Flame contact with anysurface is studiously avoided in the construction of this invention.

An apparatus by which the objects of this invention may be carried outis shown in the accompanying drawings, forming; a part-hereof, and. inwhich Figure 1 is a vertical: sectional. View on line l-I of Figure 2.Figure2ii's a sectional view on line 2-2 of Figure 1. Figure 3. is. apartial sectional view on line 33 of Figure 2 in reduced scale. Figure 4is an e1evation,.partl-y' in section of an oil pre-heater, shown inreduced scale.

Similar numerals refer tosimilar partsin the. several'views.

A- large chamber l is supported. on. uprights 2, and, it. has in it.two. opposed side headers 3-3,. having; inlet 4- and outlet 5, cold;oilcoming in the; inlet 4 and. Oil; heated to a temperature: ofapproximately-850 Fahrenheit comingoutof the outlet 5. Between theheaders are oil-carryin pipes ortubes 6 arrangedvery much, like. thetubes of a steam boiler. These-tubes 6. are=closelygrouped at: the; top.of the.- chamber l and downs wardly near the center of the chamber theyarearrangedin vertical rows so. that the lines I may be. nlacedin rowsbetween, the/ tubes; These flues; are supported: by; bands 8; and, restupon the. floor of the; chamber on stands 9.. These stands. allowfreecirculation of; air: up through. the fines from; the base; ofthe-chamber.

Passing through openings; in; the bottom of. the; chamber are! aplurality of'burner-s: Ii], one: for each flue. 'I-hese burnersI areconnected inrows fed. fromz pipes; H which; haverbackrfirer prezventersI-2=, in; them; prion to their; connection with. the manifold I 3) a:fillbstantially'completely. combustiblemixturemf fluid. 11811 such;asgas; or oil and air., It. may be; fed; by: an; industrial. carburetor:such as is illus-- tnated in. theyK'emp; et; a1; patentsrabove referred:to:vv Valves. |:4- a-nd1. I-5;irr thespipe I I-, om each side: of; the:fire preventers may be turned to. accu.-- rately control the amount ofthe: mixture enter-- ing: the pipes. Hr, andvalves I6. on: each; burnermay be: used: to: facilitate thelighting of, onea burner or a' group. ofburners turned, on: at; once.

The; burnersare lit by an igniter-insertedrthrou gh: openings. inthe:chamber; walls: covered; by flaps lt'|-.

A thermostat l:&=se.1tv.es.to. operate; a.valye on; manifold; In: tolimit; the. fuel; fed at times. when: the oil temperature. is low;so;that too m ch heat: may not suddenly be applied. Another therm0.--stat,.not'. shown; is;in; thaoir exhaust. pipe. 5; op, cratinganothervalve:- om manifold l3) to; regulate: theflow of. fuel to give. an evemaccurate predestermined; temperatureztothe: oil inztheiheaterz;

After: the; air; has been. forced them; the cham.- ber: l1,. thechamber; fiils.:wi17h-. the: heated inert; sasesproducedibythecombustiomand these gas s constantly: circmate: around the tubes; 6. andhl'fillghl'thfi, flues. 1;. going; out.- at the; top and. being; drawn.in; again; at? the bottom; in. a. constant flow. oi inert; gas; which.is constantlyheated; by theflame and; is; constantly. circulated;uppnthe tubes 6 to heat them to the desiredde iee'of Thema-niiold I 3has; fed to it' l.

approximately 850 Fahrenheit. The contacting of the tubes solely byinert ga gives them the temperature required without over-heating andwithout blistering, and should a break occur in any of the tubes by anychance, the inert gas will not support combustion and there will be noburning of the oil possibly leaking from the tubes. The. inert. gasesunder their own pressure flow from the chamber I through openings I9 inthe chamber bottom, passing to the pipes 20 and to manifold 2|. From themanifold 2| the inert gases may be led by pipe 22 through an oilpreheater 23 having bafiles 24 therein, the gases passing out at pipe25. Oil, prior to its entrance to header 3 may be passed through thispreheater 23, entering at 26, passing through pipe 21 in thepre-heater,and then passin from the pipe at 28 to the header 3. From pipe 25 thegases be passed to a heat exchanger and towers of desiccants, not shown,for use in the refinery for purging, producing inert. blanketing.atmosphere. and when compressed and dried: itcan be used for instrumentoperation.

From the. oil heater above described the oil will.

pass. directly to the. reaction chamber of the cracker,

What is claimed. asnew. and desired to besecured by Letters-Patentis:

1. A fluid heater comprising a. plurality oi closely spaced.substantially horizontally, extending, fluid carrying tubes, connectionsat the endsof said tubes to allow for the. passing. of. fluid.constantly through the tubes, a plurality ofheat? ing flues extendingupwardly between certain and. under other of said. tubes, a chamberenclosing said tubesand.fiues-,.said flues bei-ngiree. oi obstructionand spaced. from. the. bottom. and top. of. the. chamber. to.allow thefree flow of. gas from. the chamber. therethrough, burners. beneath thebottom of. the lines and: means to feed: a combustible. mixture. of airand fluid. fuel. to said. burners, said flues. enclosing. the flamefrom. the burners. and Promoting circulation of gases. to. and from. theflame, the'fiame from. the burners. setting up a continuous flow ofheated gases vertically around said tubes.

2.. Afluid heater comprising. aplurality of rowsv of substantially.vertical. heating. flues, substantially. horizontally. extending. fluid.carrying tubes,. some. extending between and. others over said. flues,connections atv the ends: of. said. tubes toallow for. the passage offluid. constantly through. the tubes, achamber enclosing said flues.and.

tubes, the fines. being. free of. obstruction. and.

spaced from the bottom. and top. of thechamber. to allow the free flowof gas from the chamber. therethrough, burnersbeneath.the-bottom of the.flues, and meansto feedacombustible mixture. oi air and, fluid fuel to,said burners, said. fiues.

enclosing the flame from the burners, the flames setting up, acontinuous. circulation. of. gases.

thrcughthe fiuesand around the tubes.

3; A; fluid heater comprisinga plurality of rows. of substantiallyvertical heating flues, substantially. horizontally extending fluidcarrying tubes,

some extending between and others. over said flues, connections at. theends of said tubes to.-

allow for thepassageoi fluid constantly through. the. tubes, a chamberenclosing said flues. and

tubes, the. fines being free of obstruction. and.

spaced; from the bottom andtop. of. the chamber. toallowthe freeflow. ofgas from the chamber therethrough, rows of burners one beneath the.bottom of eachflue, acombustible. mixture. inlet.

piperfor; each rowof burners, amanifold. for the.

group of inlet pipes, and means to feed a combustible mixture of air andfluid fuel to said manifold, said flues enclosing the flame from theburners, the flames setting up a continuous circulation of combustedgases through the flues and around the tubes.

4. A fluid heater and inert gas generator comprising a plurality ofclosely spaced substantially horizontally extending fluid carryingtubes, connections at the ends of said tubes to allow for the passing offluid constantly through the tubes, a plurality of heating fluesextending upwardly between certain and under other of said tubes, achamber enclosing said tubes and flues, said flues being free ofobstruction and spaced from the bottom and top of the chamber to allowthe free flow of gas fram the chamber therethrough, burners beneath thebottom of the flues and means to feed a combustible mixture of air andfluid fuel to said burners, said flues enclosing the flame from theburners and promoting circulation of gases to and from the flame, theflame from the burners setting up a continuous flow of heatedsubstantially inert gases vertically around said tubes and outlets fromthe bottom of said chamber for the inert gases.

5. A fluid heater and inert gas generator comprising a plurality of rowsof substantially vertical heating flues, substantially horizontallyextending fluid carrying tubes, some extending between and others oversaid flues, connections at the ends of said tubes to allow for thepassage of fluid constantly through the tubes, a chamber enclosing saidflues and tubes, the flues being free of obstruction and spaced from thebottom and top of the chamber to allow the free flow of gas from thechamber therethrough, burners beneath the bottom of the flues, and meansto feed a combustible mixture of air and fluid fuel to said burners,said flues enclosing the flame from the burners, the flames setting up acontinuous circulation of substantially inert gases through the fluesand around the tubes and outlets from the bottom of the chamber for theinert gas.

6. A fluid heater and inert gas generator comprising a plurality of rowsof substantially vertical heating flues, substantially horizontallyextending fluid carryin tubes, some extending between and others oversaid flues, connections at the ends of said tubes to allow for thepassage of fluid constantly through the tubes, a chamber enclosing saidflues and tubes, the flues being free of obstruction and spaced from thebottom and top of the chamber to allow the free flow of gas from thechamber therethrough, rows of burners one beneath the bottom of eachflue, a combustible mixture inlet pipe for each row of burners, amanifold for the group of inlet pipes, and means to feed a combustiblemixture of air and fluid fuel to said manifold, said flues enclosing theflame from the burners, the flames setting up a continuous circulationof combusted substantially inert gases through the flues and around thetubes, and outlets from the bottom of the chamber for the inert gas.

7. An oil heater for petroleum refining comprising a heating walledchamber, a series of substantially vertical open flues therein spacedfrom the top and bottom of the chamber to allow a free flow of gas fromthe chamber therethrough, each flue having a burner adjacent the bottomthereof to blast a flame within each flue, said walled chamber havingexhaust openings adjacent the bottom of the flues, and the walls of thechamber directing combustion gases toward said openings, the burningflame blasting combustion gases from the upper end of each flue anddrawing part of the combustion gases into the lower end of each flue andsetting up paths of circulation in the heater atmosphere, a plurality ofoil carrying tubes within said chamber arranged adjacent said flues andspaced from the tops thereof, and being within the paths set up by thecirculating heat from the flues.

8. The process of heating oil for petroleum crackers comprising passingoil through pipes in a chamber, feeding to a burner within the chamber acompletely combustible fuel mixture to produce a flame within thechamber, shielding the flame of combustion from contact with the oilcarrying pipes, the complete combustion of the fuel producing inertgases substantially free from oxygen and carbon monoxide and setting upa rapid circulation of the heated inert gases around the pipes, theburning fuel mixture drawing the combusted inert gases into contact withthe flame of combustion and recirculating the gases around the pipes,and maintaining the chamber under pressure of the inert gases greaterthan atmospheric pressure.

WILLIAM WALLACE KEMP.

, REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,297,589 Pavlon Mar. 18, 19191,717,115 McCann June 11, 1929 1,980,301 Stewart Nov. 13, 1934 1,756,407Vobach Apr. 29, 1930 2,206,378 Wilson July 2, 1940 2,288,368 ParsonsJune 30, 1942 2,335,317 Sherman Nov. 30, 1943 2,067,864 Stirling Jan.12, 1937 2,192,238 Ocon Mar, 5, 1940

